You have to watch this Microsoft cartoon explaining the science behind its HoloLens holographic goggles

It's voiced-over by a narrator, explaining how the HoloLens renders holograms (actually stereoscopic 3D images, if you want to get technical, according to the video), and the challenges of making it so you don't get nauseous while wearing them.

It's a little like the videos you'd watch in science class, but better, because...holograms.

Here you go:

There are lots of great little looks into how all of this will work. Basically, finding the right distance at which the holograms are visible was a real challenge, because it causes your eyes to focus differently.